Development and application of metallo-phthalocyanines as potent G-quadruplex DNA binders and photosensitizers.

Metallo-phthalocyanines (MPc) are common photosensitizers with ideal photophysical and photochemical properties. Also, these molecules have shown to interact with non-canonical nucleic acid structures, such as G-quadruplexes, and modulate oncogenic expression in cancer cells. Herein, we report the synthesis and characterisation of two metallo-phthalocyanines containing either zinc (ZnPc) or nickel (NiPc) in the central aromatic core and four alkyl ammonium lateral chains. The interaction of both molecules with G-quadruplex DNA was assessed by UV-Vis, fluorescence and FRET melting experiments. Both molecules bind strongly to G-quadruplexes and stabilise these structures, being NiPc the most notable G-quadruplex stabiliser. In addition, the photosensitizing ability of both metal complexes was explored by the evaluation of the singlet oxygen generation and their photoactivation in cells. Only ZnPc showed a high singlet oxygen generation either by direct observation or by indirect evaluation using a DPBF dye. The cellular evaluation showed mainly cytoplasmic localization of ZnPc and a decrease of the IC50 values of the cell viability of ZnPc upon light activation of two orders of magnitude. Two metallo-phthalocyanines containing zinc and nickel within the aromatic core have been investigated as G-quadruplex stabilizers and photosensitizers. NiPc shows a high G4 binding but negligible photosensitizing ability while ZnPc exhibits a moderate binding to G-quadruplex together with a high potency to generate singlet oxygen and photocytotoxicity. The interaction with G4s and capacity to be photosensitized is associated with the geometry adopted by the central metal core of the phthalocyanine scaffold.

Impact of the zinc complexation of polytopic polyaza ligands on the interaction with double and single stranded DNA/RNA and antimicrobial activity.

Metal complexes have gained a huge interest in the biomedical research in the last decade because of the access to unexplored chemical space with regards to organic molecules and to present additional functionalities to act simultaneously as diagnostic and therapeutic agents. Herein, we evaluated the interaction of two polytopic polyaza ligands and their zinc complexes with DNA and RNA by UV thermal denaturation, fluorescence and circular dichroism spectroscopic assays. The zinc coordination was investigated by X-ray diffraction and afforded the structure of the binuclear zinc complex of PYPOD. Thermal denaturation of DNA and RNA and fluorimetry analysis revealed preferential binding of the zinc-PHENPOD complexes towards GC-containing DNA in contrast to the free ligands. On the other hand, PYPOD metal complexes, compared to the free ligand, stabilized AT-based DNA (B-form) better than AU-RNA (A-form). With regards to single stranded RNA, the binuclear complex of PHENPOD and the free ligand can efficiently identify polyadenylic acid (poly A) among other RNA sequences by circular dichroism spectroscopy. The antimicrobial activity in S. aureus and E. coli bacteria showed the highest activity for the free ligands and their trinuclear zinc complexes. This work can provide valuable insights into the impact of the nuclearity of polytopic polyaza ligands in the binding to DNA/RNA and the antimicrobial effect.

Modulating the G-Quadruplex and Duplex DNA Binding by Controlling the Charge of Fluorescent Molecules.

Two fluorescent and non-toxic spirobifluorene molecules bearing either positive (Spiro-NMe3) or negative (Spiro-SO3) charged moieties attached to the same aromatic structure have been investigated as binders for DNA. The novel Spiro-NMe3 containing four alkylammonium substituents interacts with G-quadruplex (G4) DNA structures and shows preference for G4s over duplex by means of FRET melting and fluorescence experiments. The interaction is governed by the charged substituents of the ligands as deduced from the lower binding of the sulfonate analogue (Spiro-SO3). On the contrary, Spiro-SO3 exhibits higher binding affinity to duplex DNA structure than to G4. Both molecules show a moderate quenching of the fluorescence upon DNA binding. The confocal microscopy evaluation shows the internalization of both molecules in HeLa cells and their lysosomal accumulation.

Behavioural alterations induced by intermittent ethanol intake and noise exposure in adolescent rats.

Alcohol intake and exposure to noise are common activities of human adolescents performed in entertainment contexts worldwide that can induce behavioural disturbances. Therefore, the aim of the present work was to investigate in an experimental model of adolescent animals whether noise exposure and intermittent ethanol intake, when present individually or sequentially, might be able to modify different behaviours. Adolescent Wistar rats of both sexes were subjected to voluntary intermittent ethanol intake for 1 week followed by exposure to noise for 2 h and tested in a battery of behavioural tasks. Data show that males exposed to noise experienced a deficit in associative memory (AM), increase in anxiety-like behaviours (ALB) and altered reaction to novelty (RN) when compared with sham animals, whereas females also showed an increase in risk assessment behaviours (RABs) and a decrease in exploratory activity (EA). In contrast, ethanol intake induced an increase in RAB and RN in males and females, whereas females also showed a deficit in AM and EA as well as an increase in ALB. When ethanol was ingested before noise exposure, most parameters were counteracted both in male and females, but differed among sexes. In consequence, it could be hypothesized that an environmental acute stressor like noise might trigger a behavioural counteracting induced by a previous repeated exposure to a chemical agent such as ethanol, leading to a compensation of a non-adaptive behaviour and reaching a better adjustment to the environment.

Effects of early noise exposure on hippocampal-dependent behaviors during adolescence in male rats: influence of different housing conditions.

Central nervous system (CNS) development is a very complex process that can be altered by environmental stimuli such as noise, which can generate long-term auditory and/or extra-auditory impairments. We have previously reported that early noise exposure can induce hippocampus-related behavioral alterations in postnatal day (PND) 28 adolescent rats. Furthermore, we recently found biochemical modifications in the hippocampus (HC) of these animals that seemed to endure even in more mature animals (i.e. PND35) and that have not been studied along with behavioral correlates. Thus, the aim of this work was to reveal novel data about the effects of early noise exposure on hippocampal-dependent behaviors in more mature animals. Additionally, extended enriched environment (EE) housing was evaluated to determine its capacity to induce behavioral modifications, either by its neuroprotective ability or the greater stimulation that it generates. Male Wistar rats were exposed to different noise schemes at PND7 or PND15. Upon weaning, some animals were transferred to EE whereas others were kept in standard cages. At PND35, different hippocampal-dependent behavioral assessments were performed. Results showed noise-induced behavioral changes that differed according to the scheme and age of exposure used. In addition, housing in an EE was effective either in preventing some of these changes or in inducing the appearance of new behavioral modifications. These findings suggest that CNS development would be sensitive to the effects of different type of environmental stimuli such as noise or enriched housing, leading to maladaptive behavioral changes that last even until adolescence.

Alkaloids as Photosensitisers for the Inactivation of Bacteria.

Antimicrobial photodynamic therapy has emerged as a powerful approach to tackle microbial infections. Photodynamic therapy utilises a photosensitiser, light, and oxygen to generate singlet oxygen and/or reactive oxygen species in an irradiated tissue spot, which subsequently react with nearby biomolecules and destroy the cellular environment. Due to the possibility to irradiate in a very precise location, it can be used to eradicate bacteria, fungus, and parasites upon light activation of the photosensitiser. In this regard, natural products are low-cost molecules capable of being obtained in large quantities, and some of them can be used as photosensitisers. Alkaloids are the largest family among natural products and include molecules with a basic nature and aromatic rings. For this study, we collected the naturally occurring alkaloids used to treat microorganism infections using a photodynamic inactivation approach. We gathered their main photophysical properties (excitation/emission wavelengths, quantum yields, and oxygen quantum yield) which characterise the ability to efficiently photosensitise. In addition, we described the antibacterial activity of alkaloids upon irradiation and the mechanisms involved in the microorganism killing. This review will serve as a reference source to obtain the main information on alkaloids used in antimicrobial photodynamic therapy.

Noise-induced hippocampal oxidative imbalance and aminoacidergic neurotransmitters alterations in developing male rats: Influence of enriched environment during adolescence.

Living in big cities might involuntarily expose people to high levels of noise causing auditory and/or extra-auditory impairments, including adverse effects on central nervous system (CNS) areas such as the hippocampus. In particular, CNS development is a very complex process that can be altered by environmental stimuli. We have previously shown that noise exposure of developing rats can induce hippocampal-related behavioral alterations. However, noise-induced biochemical alterations had not been studied yet. Thus, the aim of this work was to assess whether early noise exposure can affect rat hippocampal oxidative state and aminoacidergic neurotransmission tone. Additionally, the effectiveness of an enriched environment (EE) as a neuroprotective strategy was evaluated. Male Wistar rats were exposed to different noise schemes at 7 or 15 days after birth. Upon weaning, some animals were transferred to an EE whereas others were kept in standard cages. Short- and long-term measurements were performed to evaluate reactive oxygen species, thioredoxins levels and catalase activity as indicators of hippocampal oxidative status as well as glutamic acid decarboxylase and a subtype of glutamate transporter to evaluate aminoacidergic neurotransmission tone. Results showed noise-induced changes in hippocampal oxidative state and aminoacidergic neurotransmission markers that lasted until adolescence and differed according to the scheme and the age of exposure. Finally, EE housing was effective in preventing some of these changes. These findings suggest that CNS development seems to be sensitive to the effects of stressors such as noise, as well as those of an environmental stimulation, favoring prompt and lasting molecular changes.

Parto gemelar diferido: a propósito de un caso / Delayed twin birth: case report

INTRODUCCIÓN: Se presenta el caso de un parto diferido en una gestación gemelar en la que se consigue retrasar el parto del segundo gemelo 45 días con manejo conservador. CASO CLÍNICO: Mujer de 25 años, gestación gemelar bicorial biamniótica, con diagnóstico de muerte fetal del primer gemelo en semana 24+3 y parto del mismo tras una semana de evolución. Se decide la opción de tratamiento conservador expectante, con reposo absoluto, manteniendo tocolisis intravenosa, controles analíticos seriados, controles cardiotocográficos diarios, profilaxis antibiótica y antitrombótica. Con ello se consigue diferir el parto un total de 45 días. CONCLUSIÓN: El parto diferido en gestaciones gemelares es una práctica poco habitual, por lo que se carece de protocolos y actuaciones específicas. La bibliografía disponible difiere en cuanto al manejo de dichos casos y en el total de días que se consigue diferir el parto, pero en todos los estudios se reporta el beneficio en términos de resultados perinatales al conseguir aumentar la edad gestacional del segundo gemelo. En nuestro caso se consiguió una mejora sustancial del resultado perinatal asociado a la prematuridad sin importantes efectos adversos maternos y tras el periodo de latencia indicado.

INTRODUCTION: We report a delayed delivery of a dichorionic diamniotic twin pregnancy, in which the birth of the second twin was postponed 45 days. CASE REPORT: At 24+3 weeks of gestation, a 25-year-old woman with dichorionic diamniotic twin pregnancy presented with preterm premature rupture of membranes and intrauterine dead of the first fetus. Spontaneous delivery of the first death twin, occurred al 25+2 weeks. Tocolysis, antibiotic, antithrombotic prophylaxis, absolute rest, serial blood tests and fetal cardiotocography controls, were performed. The second twin was delivered at 31+5 weeks, after a the preterm premature rupture of membranes triggered the labor. The interval between the first and second birth was 45 days. CONCLUSION: Delayed delivery in twin pregnancies, is an uncommon clinical situation, so there are not validated medical protocols. Available bibliography offers different practices related to its management. Most studies confirm the better survival rate and perinatal outcomes of the postponed birth twin.

Oxidative Stress-Induced Brain Damage Triggered by Voluntary Ethanol Consumption during Adolescence: A Potential Target for Neuroprotection?

Alcohol consumption, in particular ethanol (EtOH), typically begins in human adolescence, often in a "binge like" manner. However, although EtOH abuse has a high prevalence at this stage, the effects of exposure during adolescence have been less explored than prenatal or adult age exposure. Several authors have reported that EtOH intake during specific periods of development might induce brain damage. Although the mechanisms are poorly understood, it has been postulated that oxidative stress may play a role. In fact, some of these studies revealed a decrease in brain antioxidant enzymes' level and/or an increase in reactive oxygen species (ROS) production. Nevertheless, although existing literature shows a number of studies in which ROS were measured in developing animals, fewer reported the measurement of ROS levels after EtOH exposure in adolescence. Importantly, neuroprotective agents aimed to these potential targets may be relevant tools useful to reduce EtOH-induced neurodegeneration, restore cognitive function and improve treatment outcomes for alcohol use disorders (AUDs). The present paper reviews significant evidences about the mechanisms involved in EtOH-induced brain damage, as well as the effect of different potential neuroprotectants that have shown to be able to prevent EtOH-induced oxidative stress. A selective inhibitor of the endocannabinoid anandamide metabolism, a flavonol present in different fruits (quercetin), an antibiotic with known neuroprotective properties (minocycline), a SOD/catalase mimetic, a potent antioxidant and anti-inflammatory molecule (resveratrol), a powerful ROS scavenger (melatonin), an isoquinoline alkaloid (berberine), are some of the therapeutic strategies that could have some clinical relevance in the treatment of AUDs. As most of these works were performed in adult animal models and using EtOH-forced paradigms, the finding of neuroprotective tools that could be effective in adolescent animal models of voluntary EtOH intake should be encouraged.

Exposure of Developing Male Rats to One or Multiple Noise Sessions and Different Housing Conditions: Hippocampal Thioredoxin Changes and Behavioral Alterations.

Exposure of developing rats to noise has shown to induce hippocampal-related behavioral alterations that were prevented after a week of housing in an enriched environment. However, neither the effect of repeated exposures nor its impact on key endogenous antioxidants had been studied yet. Thus, the aim of the present work was to reveal novel data about hippocampal oxidative state through the measurement of possible age-related differences in the levels of hippocampal thioredoxins in rats exposed to noise at different developmental ages and subjected to different schemes and housing conditions. In addition, the possibility that oxidative changes could underlie hippocampal-related behavioral changes was also analyzed. Developing male Wistar rats were exposed to noise for 2 h, either once or for 5 days. Upon weaning, some animals were transferred to an enriched cage for 1 week, whereas others were kept in standard cages. One week later, auditory and behavioral assessments, as well as measurement of hippocampal thioredoxin, were performed. Whereas no changes in the auditory function were observed, significant behavioral differences were found, that varied according to the age, scheme of exposure and housing condition. In addition, a significant increase in Trx-1 levels was found in all noise-exposed groups housed in standard cages. Housing animals in an enriched environment for 1 week was effective in preventing most of these changes. These findings suggest that animals become less susceptible to undergo behavioral alterations after repeated exposure to an environmental challenge, probably due to the ability of adaptation to an unfavorable condition. Moreover, it could be hypothesized that damage to younger individuals could be more easily prevented by a housing manipulation.

Phenotypic and molecular traits determine the tolerance of olive trees to drought stress.

Olive trees are known for their capacity to adapt to drought through several phenotypic and molecular variations, although this can vary according to the different provenances of the same olive cultivar. We confronted the same olive cultivar from two different location in Spain: Freila, in the Granada province, with low annual precipitation, and Grazalema, in the Cadiz province, with high annual precipitation, and subjected them to five weeks of severe drought stress. We found distinctive physiological and developmental adaptations among the two provenances. Thus, trees from Freila subjected to drought stress exhibited increasing root dry weights and decreasing leaf numbers and relative stem heights. On the other hand, the treatment with drought in Grazalema trees reduced their leaf chlorophyll contents, but increased their relative stem diameter and their root hydraulic conductivity. The physiological responses of Freila tree roots to drought were linked to different molecular adaptations that involved the regulation of genes related to transcription factors induced by ABA, auxin and ethylene signaling, as well as, the action of a predicted membrane intrinsic protein (MIP). On the other hand, the responses of Grazalema trees were related with different root genes related to oxidation-reduction, ATP synthesis, transduction and posttranslational regulation, with a special mention to the cytokinins signaling through the transcript predicted as a histidine-containing phosphotransfer protein. Our results show that olive trees adapted to dry environments will adjust their growth and water uptake capacity through transcription factors regulation, and this will influence the different physiological responses to drought stress.

Molecular Cloning and Transient Expression of Recombinant Human PPARγ in HEK293T Cells Under an Inducible Tet-on System.

Peroxisome proliferator-activated receptor gamma (PPARγ) is involved in the regulation of lipid and glucose homeostasis and inflammation. PPARγ expression level has been widely studied in multiple tissues; however, there are few reports of preceding attempts to produce full-length human PPARγ (hPPARγ) in cellular models, and generally, expression level is not known or measurable. We propose an alternative strategy to express recombinant hPPARγ1, using a transient transfection with an inducible Tet-On 3G system where target and reporter gene were cloned in the same open reading frame. We transiently co-transfected human embryonic kidney 293T (HEK293T) cells with pTRE-ZsGreen1-IRES2-hPPARγ1 and pCMV-TET3G for inducible expression of hPPARγ1. Relative expression of the transcript was evaluated by RT-qPCR 48 h after transfection, obtaining a high expression level of hPPARγ (530-fold change, p < 0.002) in co-transfected HEK293T cells in the presence of doxycycline (1 µg/mL); also a significantly increased production of the reporter protein ZsGreen1 (3.6-fold change, p < 0.05) was determined by fluorescence analysis. These data indicated that HEK293T cells were successfully co-transfected and it could be an alternative model for hPPARγ expression in vitro. Additionally, this model will help to validate the quantification of inducible hPPARγ expression in vivo models for future research.

The Coming of Age in Iodane-Guided ortho-C-H Propargylation: From Insight to Synthetic Potential.

As early as 1991 Ochiai et al. reported that an acid-activated form of phenyliodine diacetate, PhI(OAc)2 , undergoes a reaction with propargyl-silanes, germanes and stannanes to give the ortho-propargyl iodobenzene. This formal C-H alkylation was proposed to take place through an unusual (even to date) iodonio-based [3,3] rearrangement of an intermediate allenylsilane. Although this mechanistic principle has been invoked in related iodane-directed C-H coupling reaction, some underlying principles have remained unaddressed, and the reaction rarely employed. Herein, DFT evidence for a mechanism best described as iodine-guided electrophilic aromatic substitution is presented. Using a newly optimized reaction protocol that significantly reduces the undesired reduction process, the potency of the method is showcased through the synthesis of >40 structurally diverse ortho-iodo propargyl (or allenyl) arenes.

Molecular Insights into the Involvement of a Never Ripe Receptor in the Interaction Between Two Beneficial Soil Bacteria and Tomato Plants Under Well-Watered and Drought Conditions.

Management of plant growth-promoting bacteria (PGPB) can be implemented to deal with sustainable intensification of agriculture. Ethylene is an essential component for plant growth and development and in response to drought. However, little is known about the effects of bacterial inoculation on ethylene transduction pathway. Thus, the present study sought to establish whether ethylene perception is critical for growth induction by two different PGPB strains under drought conditions and the analysis of bacterial effects on ethylene production and gene expression in tomatoes (Solanum lycopersicum). The ethylene-insensitive never ripe (nr) and its isogenic wild-type (wt) cv. Pearson line were inoculated with either Bacillus megaterium or Enterobacter sp. strain C7 and grown until the attainment of maturity under both well-watered and drought conditions. Ethylene perception is crucial for B. megaterium. However, it is not of prime importance for Enterobacter sp. strain C7 PGPB activity under drought conditions. Both PGPB decreased the expression of ethylene-related genes in wt plants, resulting in stress alleviation, while only B. megaterium induced their expression in nr plants. Furthermore, PGPB inoculation affected transcriptomic profile dependency on strain, genotype, and drought. Ethylene sensitivity determines plant interaction with PGPB strains. Enterobacter sp. strain C7 could modulate amino-acid metabolism, while nr mutation causes a partially functional interaction with B. megaterium, resulting in higher oxidative stress and loss of PGPB activity.

Ethylene sensitivity and relative air humidity regulate root hydraulic properties in tomato plants.

MAIN CONCLUSION: The effect of ethylene and its precursor ACC on root hydraulic properties, including aquaporin expression and abundance, is modulated by relative air humidity and plant sensitivity to ethylene. Relative air humidity (RH) is a main factor contributing to water balance in plants. Ethylene (ET) is known to be involved in the regulation of root water uptake and stomatal opening although its role on plant water balance under different RH is not very well understood. We studied, at the physiological, hormonal and molecular levels (aquaporins expression, abundance and phosphorylation state), the plant responses to exogenous 1-aminocyclopropane-1-carboxylic acid (ACC; precursor of ET) and 2-aminoisobutyric acid (AIB; inhibitor of ET biosynthesis), after 24 h of application to the roots of tomato wild type (WT) plants and its ET-insensitive never ripe (nr) mutant, at two RH levels: regular (50%) and close to saturation RH. Highest RH induced an increase of root hydraulic conductivity (Lpo) of non-treated WT plants, and the opposite effect in nr mutants. The treatment with ACC reduced Lpo in WT plants at low RH and in nr plants at high RH. The application of AIB increased Lpo only in nr plants at high RH. In untreated plants, the RH treatment changed the abundance and phosphorylation of aquaporins that affected differently both genotypes according to their ET sensitivity. We show that RH is critical in regulating root hydraulic properties, and that Lpo is affected by the plant sensitivity to ET, and possibly to ACC, by regulating aquaporins expression and their phosphorylation status. These results incorporate the relationship between RH and ET in the response of Lpo to environmental changes.

Tomato ethylene sensitivity determines interaction with plant growth-promoting bacteria.

Background and Aims: Plant growth-promoting bacteria (PGPB) are soil micro-organisms able to interact with plants and stimulate their growth, positively affecting plant physiology and development. Although ethylene plays a key role in plant growth, little is known about the involvement of ethylene sensitivity in bacterial inoculation effects on plant physiology. Thus, the present study was pursued to establish whether ethylene perception is critical for plant-bacteria interaction and growth induction by two different PGPB strains, and to assess the physiological effects of these strains in juvenile and mature tomato ( Solanum lycopersicum ) plants. Methods: An experiment was performed with the ethylene-insensitive tomato never ripe and its isogenic wild-type line in which these two strains were inoculated with either Bacillus megaterium or Enterobacter sp. C7. Plants were grown until juvenile and mature stages, when biomass, stomatal conductance, photosynthesis as well as nutritional, hormonal and metabolic statuses were analysed. Key Results: Bacillus megaterium promoted growth only in mature wild type plants. However, Enterobacter C7 PGPB activity affected both wild-type and never ripe plants. Furthermore, PGPB inoculation affected physiological parameters and root metabolite levels in juvenile plants; meanwhile plant nutrition was highly dependent on ethylene sensitivity and was altered at the mature stage. Bacillus megaterium inoculation improved carbon assimilation in wild-type plants. However, insensitivity to ethylene compromised B. megaterium PGPB activity, affecting photosynthetic efficiency, plant nutrition and the root sugar content. Nevertheless, Enterobacter C7 inoculation modified the root amino acid content in addition to stomatal conductance and plant nutrition. Conclusions: Insensitivity to ethylene severely impaired B. megaterium interaction with tomato plants, resulting in physiological modifications and loss of PGPB activity. In contrast, Enterobacter C7 inoculation stimulated growth independently of ethylene perception and improved nitrogen assimilation in ethylene-insensitive plants. Thus, ethylene sensitivity is a determinant for B. megaterium , but is not involved in Enterobacter C7 PGPB activity.

Modulation by Amino Acids: Toward Superior Control in the Synthesis of Zirconium Metal-Organic Frameworks.

The synthesis of zirconium metal-organic frameworks (Zr MOFs) modulated by various amino acids, including l-proline, glycine, and l-phenylalanine, is shown to be a straightforward approach toward functional-group incorporation and particle-size control. High yields in Zr-MOF synthesis are achieved by employing 5 equivalents of the modulator at 120 °C. At lower temperatures, the method provides a series of Zr MOFs with increased particle size, including many suitable for single-crystal X-ray diffraction studies. Furthermore, amino acid modulators can be incorporated at defect sites in Zr MOFs with an amino acid/ligand ratio of up to 1:1, depending on the ligand structure and reaction conditions. The MOFs obtained through amino acid modulation exhibit an improved CO2 -capture capacity relative to nonfunctionalized materials.

Arbuscular mycorrhizal symbiosis induces strigolactone biosynthesis under drought and improves drought tolerance in lettuce and tomato.

Arbuscular mycorrhizal (AM) symbiosis alleviates drought stress in plants. However, the intimate mechanisms involved, as well as its effect on the production of signalling molecules associated with the host plant-AM fungus interaction remains largely unknown. In the present work, the effects of drought on lettuce and tomato plant performance and hormone levels were investigated in non-AM and AM plants. Three different water regimes were applied, and their effects were analysed over time. AM plants showed an improved growth rate and efficiency of photosystem II than non-AM plants under drought from very early stages of plant colonization. The levels of the phytohormone abscisic acid, as well as the expression of the corresponding marker genes, were influenced by drought stress in non-AM and AM plants. The levels of strigolactones and the expression of corresponding marker genes were affected by both AM symbiosis and drought. The results suggest that AM symbiosis alleviates drought stress by altering the hormonal profiles and affecting plant physiology in the host plant. In addition, a correlation between AM root colonization, strigolactone levels and drought severity is shown, suggesting that under these unfavourable conditions, plants might increase strigolactone production in order to promote symbiosis establishment to cope with the stress.

Triazolopyridyl ketones as a novel class of antileishmanial agents. DNA binding and BSA interaction.

A new series of triazolopyridyl pyridyl ketones has been synthetized by regioselective lithiation of the corresponding [1,2,3]triazolo[1,5-a]pyridine at 7 position followed by reaction with different electrophiles. The in vitro antileishmanial activity of these compounds was evaluated against Leishmaniainfantum, Leishmaniabraziliensis, Leishmaniaguyanensis and Leishmaniaamazonensis. Compounds 6 and 7 were found to be the most active leishmanicidal agents. Both of them showed activities at micromolar concentration against cultured promastigotes of Leishmania spp. (IC50=99.8-26.8 µM), without cytotoxicity on J774 macrophage cells. These two compounds were also tested in vivo in a murine model of acute infection by L. infantum. The triazolopyridine derivative 6 was effective against both spleen and liver parasites forms, while 7 was inactive against liver parasites. Mechanistic aspects of the antileishmanial activity were investigated by means of DNA binding studies (UV-titration and viscosimetry). Results have revealed that these active ligands are able to interact strongly with DNA [Kb=1.14 × 10(5)M(-1) (6) and 3.26 × 10(5)M(-1) (7)]. Moreover, a DNA groove binding has been proposed for both 6 and 7. To provide more insight on the mode of action of compounds 6 and 7 under biological conditions, their interaction with bovine serum albumin (BSA) was monitored by fluorescence titrations and UV-visible spectroscopy. The quenching constants and binding parameters were determined. Triazolopyridine ketones 6 and 7 have exhibited significant affinity towards BSA [Kb=2.5 × 10(4)M(-1) (6) and 1.9 × 10(4)M(-1) (7)]. Finally, to identify the binding location of compounds 6 and 7 on the BSA, competitive binding experiments were carried out, using warfarin, a characteristic marker for site I, and ibuprofen as one for site II. Results derived from these studies have indicated that both compounds interact at BSA site I and, to a lesser extent, at site II.